Porous polystyrene resin particles containing a hydroxystyrene/divinylbenzene copolymer have hitherto been known (see, for example, patent documents 1 to 3). These porous resin particles have been used as ion-exchange resins, adsorbents, etc. A purpose of the development of such porous resin particles for use as an ion-exchange resin, adsorbent, or the like has been to enhance the adsorbing ability per unit volume of the porous resin particles by imparting functional groups as much as possible to the porous resin particles and increasing the specific surface area of the porous resin particles as much as possible.
In recent years, a method of solid-phase synthesis using porous resin particles made of, e.g., a polystyrene/divinylbenzene copolymer or the like is known as one of promising methods of peptide synthesis (see, for example, patent document 4).
In the case where porous resin particles are used as such a support for solid-phase synthesis, the porous resin particles preferably swell in an organic solvent in some degree in order that a synthesized product can be obtained in a large amount on the support. However, in the case where chemical reactions are successively conducted on a support in various organic solvents as in, e.g., the ordinary solid-phase synthesis of peptides, the following problems arise when the porous resin particles swell in different degrees in the respective organic solvents. For example, when a support packed in a columnar reaction vessel having a constant capacity is used to conduct reactions in the manner as described above, a problem concerning pressure fluctuations, etc. during the reactions arises. In addition, there is a problem that the yield in the target synthesis reaction fluctuates due to the pressure fluctuations.
Consequently, in the technical field in which porous resin particles are used as a support for solid-phase synthesis, there is a desire for the development of porous resin particles which fluctuate little in the degree of swelling depending on the kinds of organic solvents.
Patent Document 1: JP-A-52-23193
Patent Document 2: JP-A-58-210914
Patent Document 3: JP-A-5-86132
Patent Document 4: U.S. Pat. No. 6,492,460